#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<cstdlib>
#include<unistd.h>
#include<sys/types.h>
#include<sys/wait.h>

#define N 2
#define NUM 1024

using namespace std;


void Writer(int wfd)
{
    string s = "hello, I am child";
    pid_t self = getpid();
    int number = 0;
    char buffer[NUM];

    while(true)
    {
        sleep(1);
        //buffer[0] = 0;
        //snprintf(buffer, sizeof(buffer), "%s-%d-%d", s.c_str(), self, number++);
        //cout<< buffer << endl;
        //write(wfd, buffer, strlen(buffer)); 
        
        char c = 'c';
        write(wfd, &c, 1);
        number++;
        cout << number << endl;
        if(number >= 5) break; 
    }
}

void Reader(int rfd)
{
    char buffer[NUM];
    while(true)
    {
        buffer[0] = 0;
        ssize_t n = read(rfd, buffer, sizeof(buffer));
        if(n > 0)
        {
            buffer[n] = 0;
            cout << "father get a message[" << getpid() << "]# " << buffer << endl; 
        }
        else if(n == 0)
        {
            printf("father read file done!\n");
            break;
        }
        else break;

        //cout << "n: " << n <<endl; 
    }
}

int main()
{
    int pipefd[N] = {0};

    int n = pipe(pipefd);

    if(n < 0)
        return 1;
    //cout << "pipefd[0]: " << pipefd[0] << ", pipefd[1]: " << pipefd[1] << endl; 
    

    pid_t id = fork();

    if(id < 0)
        return 2;
    if(id == 0)
    {
        close(pipefd[0]);

        Writer(pipefd[1]);

        close(pipefd[1]);

        exit(0);
    }

    close(pipefd[1]);

    Reader(pipefd[0]);
    close(pipefd[0]); 
    cout << "father close read fd: " << pipefd[0] << endl; 
    sleep(5);
    
    int status = 0;
    pid_t rid = waitpid(id, &status, 0);

    if(rid < 0) return 3; 

    cout << "wait child success: " << rid << " exit code: " << ((status >> 8) & 0xFF) << " exit signal: " << (status & 0x7F) << endl; 
    sleep(5);
    cout << "father quit" << endl;


    return 0;
}
